Combustion control system



April 16, 1940- L. CUNNINGHAM 7 COMBUSTION CONTROL SYSTEM Filed Sept. 5,1935 .zhvemtor.

le wtlsllfiunnin gham,

Patented Apr. 16, 1949 UNITED STATES PATENT OFFICE COMBUSTION CONTROLSYSTEM Application September 5, 1935, Serial No. 39,253

4 Claims.

This invention relates to a combustion control system.

It is an object of this invention to provide a combustion control systemwherein the draft 5 through a boiler or furnace is varied in accordancewith the fire temperature or furnace temperature.

Another object of this invention is to provide a combustion controlsystem using a draft damper for regulating the draft through a furnaceor a boiler wherein thermostatic means responsive to fire or furnacetemperatures positions the draft damper so that a given draft may beprovided for a given fire condition.

l6 A further object of this invention is to provide a combustion controlsystem of the type described above wherein means are provided foradjusting the controlling effect of the temperature responsive meanswhereby the draft damper :0 may be adjustd to various positions for agiven fire or furnace temperature.

Still another object of this invention is to provide a combustioncontrol system of the class described above wherein means are providedfor preventing automatic operation of the draft damper and for placingthe draft damper under manual control.

Another object of this invention is to provide a combustion controlsystem for a boiler having 0 fuel supply means and draft regulatingmeans wherein the fuel supply means and the draft regulating means areboth controlled in accordance with fire temperature. I

Still another object of this invention is to pro- 5 vide a combustioncontrol system having safety devices and signal devices hooked up with afuel feeding mechanism whereby safe operation of the fuel feedingmechanism is provided.

Other objects and advantages will become ap- 0 parent to those skilledin the art upon reference to the accompanying specification, claims anddrawing in which drawing there is diagrammatically illustrated thecombustion control system of my invention.

My combustion control system, for purposes of illustration, is shown asbeing applied to a boiler generally designated at III. Boiler I Ii isshown as being provided with a fuel supply nozzle II of the powderedfuel type receiving powdered fuel through a pipe or conduit I2 from apulverizer I3. The fuel is placed in a hopper I4 and is fed to thepulverizer I3 in a manner known in the art, and the pulverized fuel isthen fed from the pulverizer I3 into the boiler II through the pipe I2.The pulverizer I3 may be operatedby an electric motor designated at I5.

Boiler I0 is shown as being provided with a stack I6 and located in thisstack I6 is a draft regulating means which may take the form of 5 adraft damper I'I. By positioning the draft damper I1 between its fullopen and its full closed positions, the draft through the boiler I0 maybe accurately regulated. The draft damper I1 is operated by a lever I8which is connected 10 to a .rack bar I9. The rack bar I9 is operated bya pinion 20 mounted on a shaft 2|.

The shaft 2I may be operated by a proportioning motor of the typeillustrated in my Pat ent No. 1,989,972 patented on February 5, 1935.For purposes of illustration in this application, I have shown the motorfor operating the damper I! to comprise a gear 22 mounted on the shaft2| and driven through a reduction gear train 23 by motor rotors 24 and25. The motor rotors 24 and 25 are operated respectively by fieldwindings 26 and 21 and upon energization of the field winding 21 thedraft damper I1 is moved towards a closed position, and uponenergization of the field winding 26 the draft damper I1 is 25v movedtowards an open position. Also mounted on the shaft 2I is a worm gear 28in operative engagement with a sector plate 29 pivoted at 30. The sectorplate 29 carries contacts 3| and 32. Also carried by the sector plate 29is a switch arm 3 33 adapted to engage either contact 3| or 32. Thesector plate 29 also carries pins 34 and 35 which are adapted to engagewith limit switches 36 and 31 respectively when the sector plate 29 ismoved to either extreme position.

The switch arm 33 is operated through spring 38 by a core or armature 39which core is moved by oppositely acting coils 40 and 4|; When the coil40 is energized more than the coil 4|, the armature 39 is moved to theleft and 40 consequently the switch arm 33 is moved into engagement withthe contact 3I. Likewise, when the coil I is energized more than thecoil 49, the armature 39 is moved to the right and consequently theswitch arm 33 is moved into engagement with the contact 32. Oppositelyacting coils l2 and 43 control an armature or core 44 which is connectedthrough a spring 45 to a pivoted switch arm 46. The switch arm 46 isadapted to engage contacts 41 and 48. When 50 coil 42 is energized morethan the coil 43, the switch arm 46 moves into engagement with thecontact 41, and when the coil 43 is energized more than the coil l2, theswitch arm 46 is moved into engagement with the contact 48.

v This invention contemplates the use of a controller designated at 58,which responds to fire or furnace temperature and may take the form ofthe controller shown and described in my Patent No. 1,765,056 patentedJune 17, 1930. For purposes of illustration in this application I haveshown this controller 58 to comprise a diaphragm 5| exposed to the firewithin the boiler I 0. The diaphragm 5| which may be of spring bronze,engages a ring 52 which may likewise be made of spring bronze and thediaphragm 5| and the ring 52 are clamped between the housings 53 and 54.The controller 50 is suitably secured to the wall of the boiler I8.Secured to the diaphragm 5| by means of a nut and screw arrangement 56,is one end of a ribbon 55. The other end of the ribbon 55 is secured tothe housing 54 by means of an adjustable tension spring 51. The ribbon55 passes over a roller 58 suitably mounted in the housing 54. Theribbon 55 may frictionally engage the roller 58 or it may be securedthereto in any suitable manner as by a pin. The roller 58 carries an arm59 having contacts 68 and 6| and a slider 62 mounted on the outer endthereof. The arm 59 extends through an opening in an insulating base 63.The insulated base 63 carries contacts 64 and 65 cooperating with thecontacts 68 and 6| respectively carried by the arm 59. The insulatedbase 63 also carries a resistance coil 66 across which the slider 62 isadapted to slide. Upon an increase in fire temperature in the boiler I8the diaphragm 5| flexes towards the right to move the arm 59 in acounter-clockwise direction as shown by the arrow designated H. Upon adecrease in fire temperature the disc 5| flexes towards the left to movethe arm 59 in a clockwise direction as shown by the arrow designated C.The contacts 68, 6|, 64 and 65 are overlapping so that in cer- 4Il tainpositions of the arm 59 contact 68 engages contact 64 and contact 6|engages contact 65. It is therefore seen that when the fire temperatureis relatively low, contact 6| is in engagement with contact 65 and theslider 62 is in a down position with respect to the coil 66. Upon anincrease in fire temperature the slider 62 moves upwardly and thecontact 68 moves into engagement with the contact 64. Upon a furtherincrease in fire temperature the slider 62 continues to move upwardlyand the contact 6| is moved out of engagement with the contact 65.

A manual control switch is designated generally at 68 and may comprise aknob or handle 69 for operating a slider 18. In one position of theslider 18 it engages an elongated automatic contact 12. In anotherposition the slider 18 engages an off contact 13. In still anotherposition the slider 18 engages a resistance coil 1I and is adapted to bemanually positioned along this resistance coil 1|.

A variable resistance is generally designated at 14 and comprises threeresistances 15, 16 and 11. Slidably engaging these resistances 15, 16and 11 are sliders 18, 19 and 88, respectively. The sliders 18, 19 and88 are moved with respect to their resistance coils by rotation of aknob or handle 8|.

A pressure controller is generally designated at 82 and may take theform of a controller shown and described in application, Serial No.743,377, filed by S. C. Shipley on September 10, 1934, now Patent No.2,080,836 of May 18, 1937. For purposes of illustration in thisapplication the pressure controller 82 is shown to comprise a pressurebellows chamber 83 connected by a pipe 84 to a source of steam pressurewithin the boiler I8.

Located in the bellows chamber 83 is a bellows which operates a plunger85 which engages a lever 86. The lever 86 is pivoted on a knife edge 81and is urged in a clockwise direction by means of an adjustable tensionspring 88. The lever 86 carries a mercury switch 98. Upon an increase inpressure the lever 86 is moved in a counter-clockwise direction againstthe action of the tension spring 89 to move the mercury switch 98 to acircuit-breaking position. Upon a decrease in pressure the tensionspring 88 moves the pivoted lever 86 in a clockwise direction to movethe mercury switch 98 to a circuit-making position. The controller 82 isalso provided with a diflferential spring arrangement 89 whereby thedifferential in pressure required to move the mercury switch 98 from acircuit-making to a circuitbreaking position and back again, may bevaried.

A start and stop switch of usual design is designated at 9| andcomprises a start button 92 and an off button 93. The start button whenpressed inwardly is adapted to bridge contacts 84 and 95 and the stopbutton 93 when pushed inwardly is adapted to break contact betweencontacts 96 and 91.

A single throw double pole switch is designated at 99 and comprisesswitch arms I88 and IIII which are adapted to engage contacts I02 andI83 respectively.

A relay is generally designated at I84 and comprises a relay coil I85which is connected in any suitable manner to switch arms I86 and I81.Upon energization of the relay coil I85, the

switch arms I86 and I81 are moved into engagement with contacts I88 andI89. Upon de-energization of the relay coil I85, the switch arms I86 andI81 are moved out of engagement with the contacts I88 and I 89 by meansof springs or gravity or any other means, not shown.

A motor starter is diagrammatically desig- I nated at H8 and comprises acoil I II operatively connected in any suitable manner to switch armsH2. The switch arms II2 are adapted to engage contacts II3 uponenergization of the coil III, and upon de-energization of the coil IIIthe switch arms II2 are moved out of engagement with the contacts H3 inany suitable manner.

Line wires H4, H5 and H6 lead from some source of power, not shown. Thecontacts II3 oi the motor starter are connected by wires H1, H8 and H9to the line wires II4, H5 and H6, respectively. The switch arms I I2 areconnected by wires I28, |2I and I22 to motor I5 so that uponenergization of the coil III of the motor starter II8 so as to move theswitch arms II2 into engagement with the contacts II 3, the motor I5 andconsequently the pulverizer I3 are placed in operation and powdered fuelis fed to the boiler I8 through the nozzle II and pipe I2.

A primary I23 of a step-down transformer I24, having a secondary I25, isconnected across the line wires H4 and H5. One end of the secondary I25is connected by wires I26, I21 and I28 to the left hand ends of thecoils 48 and 42. In a like manner the other end of the secondary I25 isconnected by wires I29 and I88 to the right hand ends of the coils 4|and 43. The junction of wires I26 and I21 is connected by a wire I3I tothe contact 88 of the variable resistance 14 and the Junction of thewires I29 and I38 is connected by a wire I32 to one end of theresistance 16 of the variable resistance 14. One end of the resistancecoil 11 is connected by wires I33 and I34 to the bottom end of theresistance coil 66 located in the controller 58. The

contact 19 of the variable resistance 14 is con nected by wires I andI36 to the upper end of the resistance coil 66. The junction of wiresI33 and I34 is connected by a wire I31 to one end of the resistance coil1| and the junction of wires I35 and I36 is connected by a wire I36 tothe other end of the resistance coil H. The Junction of the oppositelyacting coils 46 and 4| is connected by a wire I39 to the center of theresistance coil 15. The contact 18 cooperating with the resistance coil15 is connected by a wire I46 to theslider 16. The automatic" contact 12is connected by wires HI and I42 to the arm 59 of the controller 56. Theleft hand end of the coil 46 is connected by a wire I43 to the contact32 carried by the sector plate 29 and the right hand end of the coil 4|is in a like manner connected by a wire I44 to the contact 3| alsocarried by the sector plate 29. The switch arm 33 is connected by a wireI45 and a resistance I46 to the junction of the oppositely acting coils42 and 43. The line wire H5 is connected by a wire I41 to the switch arm46. The contact 46 cooperating with the switch arm 46 is connected by awire I48 to the limit switch 31 and the contact 41 is likewise connectedby a wire I49 to the limit switch 36. The limit switch 31 is alsoconnected by a wire I56 to one end of the field winding 26 and the limitswitch 36 is also connected by a wire I5I to one end of the fieldwinding 21. Field windings 26 and 21 are con nected together and to awire I52 which extends to the line wire II4.

From the above wiring connections it is seen that the left hand ends ofthe secondary I23 and the coils 40 and 42 and the lower end of theresistance coil 66 are connected together and likewise the right handends of the secondary I25 and the coils H and 43 and the upper end ofthe resistance coil 66 are connected together. It is also seen that thejunction of the coils 46 and M are connected to the slider 62cooperating with the resistance coil 66. Therefore, the secondary I25,the oppositely acting coils 46, H, 42 and 43 and the resistance coil 66are connected in parallel.

With the parts in the position shown in the drawing the slider 62 is inengagement with the center of the resistance coil 66 as a result of anormal average fire temperature, the slider 16 is in engagement with theautomatic contact 12 to position the parts for automatic operation, thevariable resistance 14 is adjusted in a midposition, the oppositelyacting coils 46, M, 42 and 43 are equally energized with the result thatneither field winding 26 or 21 is energized and the draft damper I1 isin a mid position causing a normal average draft to exist within theboiler I6.

Upon an increase in fire temperature or furnace temperature, the slider62 is moved upwardly with respect to the resistance coil 66. This causesshunting or circuiting of the coil H to decrease the energizationthereof and increase the energization of the coil 46. Due to thisunbalanced relationship of the coils 46 and H, the switch arm 33 ismoved into engagement with the contact 3I. Movement of the switch arm 33into engagement with the contact 3| completes a circuit from thesecondary I25 through wires I26, I21, I28, coil 42, resistance I46, wireI45, switch arm 33, contact 3| and wires I44 and I29 back to thesecondary I25. Completion of this circuit causes short-clrcuiting of thecoil 43 to decrease the energization thereof and increase theenergization of the coil 42. This causes movement of the switch arm 46into engagement with the contact 41 to complete a circuit from the linewire II5, through wire I41, switch arm 46, contact 41, wire I49, limitswitch 36, wire I5I, field winding 21, and wire I52 back to the linewire II4. Completion of this circuit causes energization of the fieldwinding 21 to operate the rotor 25 to move the damper I1 towards aclosed position to retard the draft gization of the oppositely actingcoils 42 and 43. 2

This balancing of the coils 42 and 43 causes movement of the switch arm46 out of engagement with the contact 41 and into the mid-position shownin the drawing. This causes breaking of the circuit through the fieldwinding 21 and consequently stops operation of the motor to maintain thedraft damper I1 in its newly adjusted position.

Upon a decrease in fire or furnace temperature the slider 62 is moveddownwardly with respect to the coil 66 which causes short-circuiting orshunting of the coil 46 to decrease the energization thereof andincrease the energization of the coil 4I. This causes movement of theswitch arm 33 into engagement with the contact 32 to complete a circuitfrom the secondary I25 through wires I29 and I36, coil 43, resistanceI46, wire I45, switch arm 33, contact 32, and wires I43, I21 and I26back to the secondary I25. Completion of this circuit causesshort-circuiting of the coil 42 to decrease the energization thereof andincrease the energization of the coil 43. This causes movement of theswitch arm 46 into engagement with the contact 48 to complete a circuitfrom the line wire II5 through wire I41, switch arm 46, contact 48, wireI48, limit switch 31, wire I56, field winding 26, and wire I52 back tothe line wire II4.

Completion of this circuit causes energization V of the field winding 26to operate the rotor 24 to move the draft damper I1 towards an openposition. Movement of the draft damper I1 towards an open positioncauses clockwise movement of the sector plate 29. When the draft damperI1 has been moved sufliciently far towards an open position asdetermined by the temperature of the fire or furnace, the contact 32 ismoved out of engagement with the contact arm 33, to cause breaking ofthe circuit through the coil 43 to cause equal energization of the coils42 and 43. Switch arm 46 is thereby moved out of engagement with thecontact 48 and to its mid-position as shown in the drawing which breaksthe circuit through the field winding 26 and stops operation of themotor controlled thereby. Draft damper I1 is therefore maintained in itsnewly adjusted position.

. If the draft damper I1 should be moved to its full closed position,the pin 34 causes opening of the limit switch 36 to prevent furtherclosing movement of the damper I1. In a like manner, when the draftdamper I1 is moved to its full open position, the pin 35 opens the limitswitch 31 to prevent further opening movement of the draft damper I1.

' respect to the coil 66 to increase the energization of the coil 40 anddecrease the energization of the coil H, which causes movement of thedamper I1 towards a closed position. Therefore,

by moving the sliders 18, 19 and 80 towards the right with the slider 62in a given position with respect to its resistance coil 66, the damperI1 is moved towards a closed position. Likewise, when the sliders 18, 19and 80 are moved toward the left, more resistance is placed in circuitwith the coil H and less resistance is placed in circuit with the coil40, which produces the same effect as if the slider 62 were moveddownwardly with respect to its coil 66. This increases the energizationof the coil 4| and decreases the energization of the coil 40 to move thedamper I1 towards an open position. Therefore with the slider 62 locatedin a given position with respect to its coil 66, movement of thecontacts 18, 19 and 80 towards the left causes opening movement of thedamper I1. Movement of contact 18 in either direction with respect toits resistance adds resistance to the circuits through both of the coilsand 4| so that in case the sliders 19 and 80 are moved to either extremeposition, burning out of the coils 40 and H is prevented. In this mannermanual means are provided for adjusting the controlling action of thecontroller with respect to damper I1 so that the damper I1 may bepositioned in a given number of different positions when the fire orfurnace temperature is at a given value This provides an easy means forcalibrating this portion of the control system.

The above detailed operation was set forth on the assumption that theslider 10 was in engagement with the automatic contact 12. Movement ofthe slider 10 out of engagement with the automatic contact 12 breaks thecircuit through the slider '62 to prevent operation of the damper I1 bythe controller 50. Since the lower end of the resistance coil H isconnected to the lower end of the resistance coil 66 and the upper endof the coil 1| is connected to the upper end of the coil 66, movement ofthe slider 10 out of engagement with the contact 12 and into engagementwith the resistance coil 1|, takes the control of the damper I1 awayfrom the controller 50 and places it under the control of the manualcontrol switch 66. Since the corresponding ends of the coils 1I and 66are connected together, movement of the slider 10 upwardly with respectto the coil 1I, causes closing movement of the damper I1 in the mannerabove described and movement of the slider 10 downwardly with respect tothe resistance coil 1I causes opening movement of the draft damper I1 inexactly the same manner as pointed out above. Movement of slider 10 outof engagement with the resistance coil H, and out of engagement with theautomatic contact 12, and into engagement with off contact 13, preventscontrol of the draft damper I1 by either the automatic controller 50 orthe manual controller 68. Therefore. manually operable means areprovided for rendering the automatic control of the draft damper I1inoperative, for placing the control of the damper I1 under manualcontrol or for preventing either automatic or manual control of thedraft damper I1.

A primary I of a step-down transformer I56, having a secondary I51, isconnected across the line wires H5 and I I6, one end of the secondaryI51 is connected by wires I58 and I59 to one of the electrodes of themercury switch 90 of the pressure controller 62. The other electrode ofthe mercury switch 90 is connected by wires I60, I6I and I62 to thecontacts 95 and 96 of the start and stop switch SL The start contact 94is connected by a wire I63 to one end of the relay coil I05. The otherend of the relay coil I05 is connected by a wire I64 to the other end ofa secondary I51. Stop contact 91 is connected by wires I65 and I66 tothe stationary contact 64 of the controller 50. and MI is connected bywires I61 and I68 to the contact I08 of the relay I04. Switch arm I06associated with the contact I08 is connected by The junction of wire I42I b a wire I69 to the junction of wire I63 and the relay coil I05.

Movement of the start button 92 into engagement with the start contacts94 and 95 completes a circuit from the secondary I51 through wires I58and I59, mercury switch 90, wires I and I6I, contact 95, start button92, contact 94, wire I63, relay coil I05 and wire I64 back to thesecondary I51. Completion of this circuit causes energization of therelay coil I05 to move the switch arms I06 and I01 into engagement withtheir contacts I08 and I09. Movement of theswitch arm I06 intoengagement with the contact I08 completes a maintaining circuit from thesecondary I51 through wires I58 and I59, mercury switch 90, wires I60and I62, contact 96, stop button 93, contact 91, wires I and I66,contacts 64 and 60, arm 59, wires I42, I61 and I69, contact I08, switcharm I06, wire I69, relay coil I05 and wire I64, back to the secondaryI51. This maintaining circuit maintains the relay coil I05 energizedregardless of the position of the start button 92. However, included inthis maintaining circuit is the pressure controller 92, the contacts 60and 64 of the controller 50 and the stop button 93 of the start and stopswitch 9I. If the boiler pressure should become too high so as to movethe mercury switch to a circuit breaking position, or if the fire orfurnace temperature should decrease below a given value so as to movethe contact 60 out of engagement with the contact 64, or if the stopbutton 93 should be pressed to break contact between the contacts 96 and91, the maintaining circuit through the relay coil I05 would be brokento cause de-energization of the same to move the switch arms I06 and I01out of engagement with the contacts I08 and I09. Since the startingcircuit for the relay coil I05 is completed through the starting button92, start button 92 must again be moved into engagement with the startcontacts 94 and 95 to again cause energization of the relay coil I05.Therefore, the relay coil I05 may only be initially energized uponmanipulation of the start button 92 and will only be maintained in anenergized condition when the boiler pressure is normal and when thecondition of the fire is normal.

The contact I09 of the relay I 04 is connected by wires I10 and HI tothe line wire II5. The switch arm I01 cooperating with the contact I09is connected by a wire I12 to one end of the coil III of the motorstarter H0. The other end of the coil III is connected by wires I 10 andI14 to the line wire IIO. Therefore, upon energization of the relay coilI05 in the manner above described, to move the switch arm I01 intoengagement with the contact I00, the coil III is energized to move theswitch arms II2 into engagement with contacts IIO to cause operation ofthe motor I5 and the fuel pulverizer I3 to supply fuel to the boiler I0.

The switch arm I01 is connected by a wire I15 to one end of a primaryI16 of a step-down transformer I11, having a secondary I10. The otherend of the primary I16 is connected by a wire I19 to the junction ofwires I10 and I14. Therefore, when the relay coil I05 is energized tomove the switch arm I01 into engagement with the contact I09, thetransformer I11 is energized simultaneously with the motor starter IIO.One end of the secondary I10 is connected by a wire I00 to the junctionof wires I and I 50. The stationary contact 05 of the controller 50 isconnected by a wire IOI to an indicating device I 02 which may take theform of an alarm or bell of usual design. The indicating device I02 isconnected by a wire I00 to the other end of the secondary I10. When thefire temperature decreases to a given value so as to cause simultaneousengagement of overlapping contacts 60, 04 and BI and 65, a circuit iscompleted from the secondary I10 through wires I00 and I50, mercuryswitch 00, wires I00 and I62, contact 06, stop button 03, contact 91,wires I65 and I06, contacts 64, 60, 0I and 05, wire IOI, alarm I02 andwire I03 back to the secondary I10. Completion of this circuit causessounding of the alarm I02 to notify the attendant in charge of thecombustion control system that the condition of the fire within theboiler I0 is abnormal.

Summarizing briefly that portion of the combustion control systemrelating to the fuel feeding mechanism, when the fire within the boilerI0 is extinguished, the arm 59 is in a down position whereby contacts 00and 04 are broken and contacts 6| and 05 are made. To start operation ofthe fuel supplying means, start button 92 is pressed inwardly tocomplete the above referred to starting circuit which causes starting ofthe fuel pulverizer I0 with consequent delivery of pulverized fuel fromthe boiler I 0. This pulverized fuel is ignited in any suitable manner,not shown, and from that point the fire temperature will tend toincreas.' An increase in fire temperature causes upward movement of arm50 to move the contact into engagementwith the contact 64, it beingremembered that the contact 6I is still in engagement with the contact65.

Therefore, when the contact 00 moves into engagement with the contact64, the circuit'through the alarm is completed and the alarm is soundedto notify the engineer in charge of the combustion control system thatcontact has been established between the contacts 00 and 04. Theengineer in response to this alarm releases the start button 92 andsince the contact between the contacts and 64 is established, themaintaining circuit is completed to maintain the fuel feeding means inoperation. Continued rise in fire temperature causes positioning of thedraft damper I1. If by reason of clogging of the nozzle II or by anyother reason, the fire within the boiler I0 should decrease through apredetermined low value, the arm 50 is moved downwardly to make contactbetween the contacts 6I and to sound the alarm I 02 to notify theengineer of faulty operation of the fuel, feeding means. If the faultyoperation is not corrected, the arm 59 continues to move downwardly tobreak contact between the contacts 60 and 04 to break the above referredto maintaining circuit to shut down the fuel feeding means, which canonly be started again after manual manipulation of the start button 92.

The contact I02 of the single throw double pole manual switch 90 isconnected by a wire I04 to the junction of wires I61 and I00. The switcharm I00 is connected by a wire I05 to the junction of wires I65 and I66.By reason of these connections it is seen that the manual switch 09 isconnected in parallel with the contacts 60 and 04 so that when theswitch arm I00 is moved into engagement with the contact I02, thecontacts 60 and 64 are rendered inoperative to control the fuelpulverizer I0. In this manner the safety function of the controller 50may be eliminated. As a safeguard to notify the engineer in charge thatthe safety function of the controller 50 is rendered inoperative, theswitch arm IOI is connected by a wire I01 to a light I00 which in turnis connected by a wire I00 to the junction of wire I10 and the primaryI16. The contact I00 cooperating with the switch arm I M is connected bya wire I00 to the junction of wires I10 and HI. By reason of theseconnections when the switch arm I00 is moved into engagement withcontact I02 to render the safety function of the controller 50inoperative, the light I60 is lit to notify the engineer of this fact.

From the above it is seen that I have invented a novel combustioncontrol system wherein a draft regulating means is positioned inaccordance with fire or furnace temperatures, wherein a fuel supplyingmeans is manually placed in operation and is under the control of safetydevices so that if the fire should assume an abnormal condition or ifthe boiler pressure should exceed a given amount, the fuel supplyingmeans will be rendered inoperative, wherein the draft regulating meansmay be adjustably positioned with respect to the fire or furnacetemperature, wherein means are provided for rendering the automaticcontrol means for the draft regulating means inoperative and placing thedraft regulating means under manual control, and wherein an alarm systemis provided for notifying the engineer when the condition of the fire isabnormal.

Although for purposes of illustration I have disclosed one form of myinvention, changes and modifications thereof may become apparent tothose skilled in the art, and consequently the scope of this inventionis to be limited only by the scope of the appended claims and prior art.

I claim as my invention:

1. In a combustion control system, in combination, means forming acombustion chamber, means for supplying. fuel to said combustionchamber, means comprising a manually depressible switch device forinitiating operation of said fuel supplying means, said switch beingclosed only when held in depressed position, means responsive to acondition indicative of the presence of combustion in the combustionchamber, said last means being operable to cause continued operation ofsaid fuel supplying means independently of said switch'when propercombustion occurs in the combustion chamber, signal means forautomatically indicating when operation of said fuel supplying means isindependent of said switch whereby uponstarting of the system thepresence of a human operative is required until proper combustion isassured by the signal whereupon the manually depressible switch may bereleased.

2. In a combustion control system, in combination, means forming acombustion chamber, means for supplying fuel to said combustion chamber,means comprising a manually depressible switch device for initiatingoperation of said fuel supplying means, said switch being closed onlywhen held in depressed position, means responsive to a conditionindicative of the presence of combustion in the combustion chamber, saidlast means being operable to cause continued operation of said fuelsupplying means independently of said switch when proper combustionoccurs in the combustion chamber, signal means for automaticallyindicating when operation of said fuel supplying means is independent ofsaid switch whereby an operative may then release the switch, and saidcondition responsive means comprising means operative upon an increaseof combustion to terminate the signal given by said signal means wherebythe operative is apprised of the establishment of combustion and of thesatisfactory progress of combustion thereafter.

3. In a combustion control system, in combination, means forming acombustion chamber, means for supplying fuel to said combustion chamber,means comprising a manually depressible switch device for initiatingoperation of said fuel supplying means, said switch being closed onlywhen held in depressed position, means responsive to a conditionindicative of the presence of combustion in the combustion chamber, saidlast means being operable to cause continued operation of said fuelsupplying means independently of said switch when proper combustionoccurs in the combustion chamber, signal means for automaticallyindicating when operation of said fuel supplying means is independent ofsaid switch whereby an operative may then release the switch, and saidcondition responsive means comprising means operative upon an increaseof combustion to terminate the si nal given by said signal means wherebythe operative is apprised of the establishment of combustion and of thesatisfactory progress of combustion thereafter, and said conditionresponsive means being arranged to cause said signal means to give asignal and to terminate said signal to indicate substantial terminationof combustion in said combustion chamber.

4. In a combustion control system, in combination, means forming acombustion chamber, means for supplying fuel to said combustion chamber,draft regulating means for said combustion chamber, means comprising amanually depressible switch device for initiating operation of said fuelsupplying means, said switch being closed only when held in depressedposition, means responsive to the fire condition in said combustionchamber, said last means being operable to cause continued operation ofsaid fuel supplying means independently of said switch when propercombustion occurs in the combustion chamber whereby said switch may bereleased, said condition responsive means includ ing means operable toassume control of the draft regulating means when operation of said fuelsupplying means becomes independent of said switch, signal means forautomatically indicating when operation of said fuel supplying means isindependent of said switch and said condition responsive means iscontrolling said draft regulating means, said condition responsive meanscausing the signal given by said signal means to be terminated after anincrease in combustion in said combustion chamber, said conditionresponsive means relinquishing control of said draft regulating meanssubstantially upon the termination of combustion, and said conditionresponsive means causing said signal means to indicate when saidcondition responsive means relinquishes control of said draft regulatingmeans.

LEWIS L. CUNNINGHAM.

